This invention relates to the mechanic arts, and comprises an arrangement for conveniently and economically cleaning air filters, particularly hollow cylindrical pleated paper filters. Such filters are well known and accepted for use in various applications, and are usually installed so that the air flow through them is from the outside to the inside. When such a filter has seen a period of use the particulate matter trapped on its outer surface increases its resistance to the passage of air beyond what can be tolerated, and the filter is then replaced and discarded.
A common use for filters of this sort is as air cleaners in farm tractors, earth moving equipment, and so forth. In such environments, the service demanded of air cleaners is especially severe, the very use of the tractor often raising clouds of dust which surround the vehicle. In such service, the period of use before a filter is intolerably loaded with particulate matter is frequently a mere matter of days, and replacement costs become prohibitive.
An obvious solution to this problem is to clean the filter and replace it, rather than discarding it, and a number of rough and ready cleaning procedures have been tried. Simplest, and least effective, is to remove the filter and jar or shake it to cause the accumulated dust to fall off the collecting surfaces. Washing with water from a hose can be performed, as can blowing off the dust by compressed air when the farmer has the air available. Water softens the paper and may convert some of the dirt to mud which soaks into the paper: the water itself may remain in portions of the filter for some period of time, not only partially obstructing the filter, but attracting dust particles in a way which makes them even more difficult to remove later. Compressed air cleaning in the reverse direction is often effective, but is also often found to physically damage the filters by reason of the excessive force unavoidably exercised by air impinging on limited areas of the filter. Pleated paper filters do not have the ability to withstand the forces involved, and fail during cleaning.